This invention relates generally to mattress foundation structures and more particularly to a box spring assembly of a type which utilizes non-coil springs. Box spring assemblies of this general type have been known since 1964, the first such spring assembly being disclosed in U.S. Pat. No. 3,286,281. Subsequently issued patents disclosing the same general type of box spring assembly are: U.S. Pat. Nos. 3,487,480; 3,506,987; 3,574,240; 3,574,241; 3,665,529; 3,680,157; 3,755,833; 3,824,639; and 3,852,838. Box spring assemblies of the general type shown in the above list of patents, all of which are assigned to the assignee of this application, are advantageous with respect to the conventional box spring assemblies using coil springs because they provide a desired stiffer foundation for the mattress and contain a reduced amount of wire. These box spring assemblies are also advantageous from the standpoints of prolonged service life, ease of assembly, and cost of manufacture.
Additional box spring assemblies of this general type are shown in U.S. Pat. Nos. 3,596,299; 3,722,013; 3,825,960; 3,833,948; 3,835,485; 3,869,740; 3,990,121; and 4,000,531.
The present invention provides a box spring assembly which utilizes a different spring from the formed wire springs utilized in the patented box spring assemblies discussed above. The spring in the present box spring assembly can be constructed of minimum width thereby imparting versatility to the assembly in terms of strength, stiffness, and cost because the number of springs used can readily be varied, this versatility being an inherent feature of the spring achieved by virtue of the spring configuration. Furthermore, the spring is constructed with a combination of arcuate bendable portions and torsion bars enabling it to resist loads in both bending and torsion to achieve an efficient use of spring material.
It is an object of the present invention, therefore, to provide an improved box spring assembly having springs with upright arcuate portions that resist bedding loads by bending.